The concept of fractional dimensional space is used to study the spontaneous emission lifetimes of excitons in quantum confined systems. We focus on a parameter α, a measure of dimensionality of the confined system and which is related to the exciton coherence volume. An analytical expression for the exciton spontaneous emission lifetime is derived and is used to calculate free exciton lifetimes in GaAs/A1 xGa 1-x As quantum wells for known values of α. Our results confirm that a minimum in the exciton lifetime occurs at a critical size of the well width (quantum well) or lateral width (quantum wire).
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